HDPE/sPS共混体系结构与性能的研究

用2种分子量不同的苯乙烯-(乙烯/丁烯)-苯乙烯三嵌段共聚物(SEBS)和一种苯乙烯-b-乙烯/丁烯(SEB)两嵌段共聚物为增容剂,对高密度聚乙烯(HDPE)/间规聚苯乙烯(sPS)共混物进行增容.采用扫描电镜(SEM)及拉伸试验研究了增溶剂的分子量及结构对共混物形态结构及力学性能的影响.结果表明:3种增容剂SEBS(SEB)均可有效地降低sPS分散相的尺寸并增加HDPE/sPS共混物的界面强度,从而提高其力学性能.sPS 的掺入可以显著提高HDPE的耐热性能.     

SEBS分子量和分子结构对其共混物性能的影响

研究了苯乙烯-乙烯/丁烯-苯乙烯嵌段共聚物(SEBS)分子量和分子结构对其共混物的力学性能、永久压缩变形和流变性能的影响。结果表明:高分子量的线型SEBS拥有更优的力学性能,更低的高温永久压缩变形;当SEBS的分子量大于临界分子量(7×104~10×104 g/mol之间)时,其室温永久压缩变形不受分子量和分子结构的影响;星型SEBS较线型含有更多的二嵌段苯乙烯-乙烯/丁烯(SEB),其分子量越高,二嵌段SEB含量越高;SEBS的分子量越大,苯乙烯含量越高,共混物的熔体黏度就越大,表观剪切黏度对剪切速率的敏感性越强。     

混合增容剂对HDPE/sPS共混物形态及性能的影响

分别采用2种组成相近而分子量不同的苯乙烯-乙烯/丁烯-苯乙烯共聚物(SEBS)以及两者的混合物对高密度聚乙烯/间规聚苯乙烯(HDPE/s PS)共混物进行增容改性。通过扫描电镜(SEM)及拉伸实验试验考查了增容剂的分子量及含量对HDPE/s PS共混物形态结构及力学性能的影响。结果表明:两种增容剂都能降低s PS分散相尺寸,使两相界面的粘合力增强。相对较低分子量的SEBS(K1652)能显著提高两相界面粘结性,进而能有效提高共混物的拉伸强度,而较高分子量的SEBS(K1651)能显著改善共混物的韧性。一定比例混合的共聚物作为增容剂在改善共混物性能方面具有协同效应,可以同时提高共混物拉伸强和断裂伸长率,混合增容剂效果优于单一增容剂。HDPE/s PS共混物中加入质量分数4%的K1652和2%的K1651,共混物的综合力学性能最优。     

PP/HDPE/弹性体三元共混改性的研究

用双螺杆挤出机制备了聚丙烯(PP)/高密度聚乙烯(HDPE)/弹性体三元共混物,分别探讨了3种弹性体乙烯-辛烯嵌段共聚物(OBC)、苯乙烯-丁二烯-苯乙烯嵌段共聚物(SBS)、苯乙烯-乙烯/丁烯-苯乙烯嵌段共聚物(SEBS)的含量对PP三元共混物力学性能的影响,并通过扫描电子显微镜观察其脆断表面形态。结果表明,OBC、SBS、SEBS和HDPE都对PP起到了一定的协同增韧作用,SEBS对PP的增韧效果最佳;SEM表明三元共混力学性能与相形态密切相关;所制备的PP/HDPE/OBC三元共混物的加工性能较好。     

顺酐化聚苯乙烯对PVC/SEBS共混物的增容作用

以顺酐化聚苯乙烯(PS-g-MAH)为增容剂,研究了苯乙烯-乙烯-丁烯-苯乙烯嵌段共聚物(SEBS)对聚氯乙烯(PVC)的共混增韧改性,讨论了该共混物在常温、低温下的力学性能及动态力学性能。结果表明,PS-g-MAH能明显改善SEBS与PVC的相容性,使PVC/SEBS共混物中分散相颗粒尺寸明显减小,分布更均匀,共混物的玻璃化转变温度内移,常温和低温下缺口冲击强度增大。当PVC/PS-g-MAH/SEBS(质量比)为75/6/25时,共混物的常温缺口冲击强度为50.6 kJ/m2,低温(-20℃)缺口冲击强度为29.8 kJ/m2。     

关于PS/PP系共混物的研究——第1报 PS/PP共混体系的相容性和相态结构

本研究以苯乙烯—乙烯—丁烯—苯乙烯嵌段共聚物(SEBS)和苯乙烯—乙烯—丙烯嵌段共聚物(SEP)为界面活性剂(相溶化剂),研究聚苯乙烯等规聚丙烯(PS/PP)共混体系的相容性;研究PS/PP两成分体系和添加界面活性剂后三成分体系的相态结构及相界面形态。为制取结构稳定的PS/PP系共混物,进一步制取具有特殊性能约PS/PP共混纤维提供实用的工艺条件和理论依据。     

POE-g-MAH改性SEBS/OBC共混物的相容性、结构和力学性能研究

采用相容剂马来酸酐接枝乙烯-辛烯无规共聚物(POE-g-MAH)改性氢化苯乙烯-丁二烯-苯乙烯嵌段共聚物/乙烯-辛烯嵌段共聚物(SEBS/OBC)共混物,研究共混物的流动性、结晶行为、微观结构及力学性能。结果表明:POE-g-MAH和OBC的加入改善SEBS流动性。当OBC的含量为40%,SEBS/OBC/POE-g-MAH的熔体流动速率(MFR)为4.43 g/10min。POE-g-MAH提高了SEBS/OBC共混物的结晶温度,改善OBC和SEBS之间的相容性。POE-g-MAH提高了SEBS与OBC之间的界面结合能力,从而提高SEBS/OBC的拉伸强度。当OBC含量为10%时,SEBS的拉伸强度和断裂伸长率提升较少,SEBS的结构对性能影响占主导。当OBC含量进一步增加时,SEBS和OBC的共同作用,明显改善共混物的拉伸强度和断裂伸长率。     

SEBS增韧PVDF的研究

采用不同结构热塑性弹性体苯乙烯-乙烯-丁烯-苯乙烯(SEBS)作为增韧剂添加到聚偏氟乙烯(PVDF)中以提高韧性;并探索两种相容剂聚丙烯接枝马来酸酐(PP-g-MAH)和苯乙烯-(乙烯-丁烯)-苯乙烯嵌段共聚物接枝马来酸酐(SEBS-g-MAH)对PVDF/SEBS共混体系物理机械性能的影响。结果表明,线型结构的SEBS有利于提高PVDF的拉伸韧性,相容剂SEBS-g-MAH有助于进一步提高拉伸韧性,其用量在1%时共混体系的断裂伸长率达到最大值。     

PA66/SEBS复合材料的制备与性能研究

以聚酰胺66(PA66)和苯乙烯-乙烯-丁二烯-苯乙烯嵌段共聚物(SEBS)为原料,3份马来酸酐接枝苯乙烯-乙烯-丁二烯-苯乙烯共聚物(SEBS-g-MAH)为增容剂,通过熔融共混法制备了PA66/SEBS复合材料,研究了SEBS添加量对复合材料结晶性能、热性能、界面相容性、力学性能等的影响。结果表明:SEBS的加入没有改变PA66的特有晶型,仅仅改变了不同晶型的相对含量;随着SEBS用量的增加,PA66/SEBS复合材料的熔融温度、界面相容性下降,拉伸强度也呈逐渐降低的趋势;随着SEBS用量的增加,未加增容剂的复合材料的断裂伸长率呈逐渐减小的趋势,而加入增容剂的复合材料的断裂伸长率则呈先增后减的趋势;另外,加入了增容剂的复合材料的力学性能明显优于未加增容剂的复合材料。     

弹性非织造布用SEBS/PP共混料的制备及其可纺性研究

以低相对分子质量苯乙烯-乙烯-丁烯-苯乙烯嵌段共聚物(SEBS)和聚丙烯(PP)为原料,制得SEBS/PP共混料,然后通过熔融纺丝制备弹性非织造布用SEBS/PP纤维,研究了SEBS/PP共混体系的流变性能、热学性能和力学性能,并对其可纺性进行了探索.结果表明:在低相对分子质量SEBS中添加高熔体流动指数PP后,可在保...     

Compatibilization effects of block copolymers in high density polyethylene/syndiotactic polystyrene blends

Three triblock copolymers of poly[styrene-b-(ethylene-co-butylene)-b-styrene] (SEBS) of different molecular weights and one diblock copolymer of poly[styrene-b-(ethylene-co-butylene)] (SEB) were used to compatibilize high density polyethylene/syndiotactic polystyrene (HDPE/sPS, 80/20) blend. Morphology observation showed that phase size of the dispersed sPS particles was significantly reduced on addition of all the four copolymers and the interfacial adhesion between the two phases was dramatically enhanced. Tensile strength of the blends increased at lower copolymer content but decreased with increasing copolymer content. The elongation at break of the blends improved and sharply increased with increments of the copolymers. Drop in modulus of the blend was observed on addition of the rubbery copolymers. The mechanical performance of the modified blends is strikingly dependent not only on the interfacial activity of the copolymers but also on the mechanical properties of the copolymers, particularly at the high copolymer concentration. Addition of compatibilizers to HDPE/sPS blend resulted in a significant reduction in crystallinity of both HDPE and sPS. Measurements of Vicat softening temperature of the HDPE/sPS blends show that heat resistance of HDPE is greatly improved upon incorporation of 20 wt% sPS.     

Hybrid anion exchange membranes with adjustable ion transport channels designed by compounding SEBS and homo-polystyrene

Hybrid anion exchange membranes (AEMs) were prepared via chemically functionalizing and crosslinking poly(styrene-b-[ethylene-co-butylene]-b-styrene) (SEBS) copolymers and low molecular weight homo-polystyrene (hPS). Via sequential chloromethylation, crosslinking, quaternization, and alkalization, a series of hPS/SEBS AEMs were obtained with varying content of hPS. Systematic structural, morphological, mechanical, absorption, and transport measurements reveal that these properties depend on the total PS content in the membranes. Particularly, increasing total PS content causes (a) PS domains in the AEMs transition the cylindrical morphology to lamella-like morphology with comparable correlation length; (b) Young's modulus, water uptake, swelling ratio, ionic exchange capacity and ionic conductivity of the AEMs, and T_g of PS phase increase. In addition, the alkaline stability of the hPS/SEBS AEMs is also improved by addition of hPS. These findings suggest that the proposed method can develop high performance SEBS AEMs that are suitable for fuel cell applications.     

Viscoelastic properties of homogeneous block copolymers

The molecular theory of Rouse-Bueche-Zimm has been modified to predict the viscoelastic behavior of homogeneous block copolymers. The model consists of beads and springs whose magnitudes correspond to the types of blocks in the polymer. Maximum relaxation times can be computed by this model. Viscoelastic data for poly(styrene-b-α-methyl styrene-b-styrene), poly(α-methyl styrene-b-styrene-b-α-methylstyrene) and poly(styrene-b-α-methyl styrene) were determined by stress relaxation methods. The results compare favorably with those predicted by the theory.     

Synthesis of high performance organic–inorganic composite via click coupling of block polymer and polyhedral oligomeric silsesquioxane

Novel hybrid systems based on poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS) and a polyhedral oligomeric silsesquioxane (POSS) have been synthesized via click chemistry. Different compositions of SEBS-functionalized POSS were obtained from the reaction of azide-functionalized styrene units of SEBS with alkyne-functionalized POSS molecules. Characterization of SEBS-functionalized POSS by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and nuclear magnetic resonance spectroscopy revealed that the POSS molecules were successfully attached to the phenyl group of the SEBS polymer chain following the click reaction. Homogeneous dispersion of POSS molecules in the polymer matrix was demonstrated by scanning electron microscopy. The POSS molecule showed excellent compatibility with polymer matrix, and as a consequence the remarkable enhancement of mechanical properties (breaking stress = 44%, modulus = 285%) and thermal stability for the resulting composite films was achieved. The reinforcing effect is ascribed to both the compatible homogeneous dispersion of POSS in the matrix and the covalent bond between SEBS and POSS molecules arising from the click coupling.     

Effect of diblock copolymers on morphology and mechanical properties for syndiotactic polystyrene/ethylene‐propylene copolymer blends

Interfacial agents are often used to compatibilize immiscible polymer blends. They are known to reduce the interfacial tension, homogenize the morphology, and improve adhesion between phases. In this study, two diblock copolymers of styrene/ethylene‐propylene (SEP), which have different molecular weights, were used to compatibilize a blend of syndiotactic polystyrene (sPS) 75% and ethylene‐propylene rubber (EPR) 25% so as to extend the applications of sPS as incoming thermoplastics. The morphological analysis and emulsification curve, which relates the average size of the dispersion particles to the concentration of diblock copolymers added, was used to investigate the efficiency of the interfacial agents on the blend morphology. A notched izod impact test and a tensile test were also performed to determine the compatibilization effect of different molecular weight copolymers on the mechanical properties of the blends and to establish links between morphology and mechanical properties. Results suggest that the lower molecular weight diblock copolymer showed an effective emulsifying capacity for sPS/ERP immiscible blend in morphology and mechanical properties. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91:3618–3626, 2004     

Improving hemocompatibility of styrene-b-(ethylene-co-butylene)-b-styrene elastomer via N-vinyl pyrrolidone-assisted grafting of poly(ethylene glycol) methacrylate

In this work, in order to enhance the grafting degree, N-vinyl pyrrolidone (NVP) was used to assist the melt grafting of the macromonomer-poly(ethylene glycol) methyl ether methacrylate (PEGM)-which has good hemocompatible property, onto styrene-b-(ethylene-co-butylene)-b-styrene (SEBS) elastomer with free radical initiator. The grafting degree of PEGM with NVP assistance was increased by at least 4-fold to those without NVP. In addition, side reactions such as homopolyerization of the PEGM monomer during the melt grafting process could be largely reduced in the NVP-assisted system. Both the hydrophilicity and hemocompatibility of the PEGM modified SEBS were highly improved. Comparing to virgin SEBS, the amount of fibrinogen adsorption was reduced by up to 75% in the NVP-assisted grafting samples.     

电场作用下磺化聚苯乙烯微球在弹性体中梯度结构构建及性能研究

先采用硫酸对聚苯乙烯微球经过磺化得到带正电荷的磺化聚苯乙烯(s PS),将s PS分散在聚二甲基硅氧烷(PDMS)预聚体中,在高压直流电场下通过电泳作用形成梯度结构,再通过PDMS的热固化后将梯度结构固定下来。采用马尔文Zeta电位仪分析了s PS微球电荷,扫描电镜(SEM)对s PS以及s PS/PDMS梯度膜的结构进行表征,动态热机械分析仪测试了材料的动态力学行为和介电损耗。结果表明,电压强度为500 V/mm时,s PS能够在PDMS预聚体中通过电泳作用形成梯度结构,s PS总质量分数为20%时,s PS/PDMS梯度膜相比相同组成的均匀膜断裂伸长率提高了9. 41%,损耗因子在所测得温度范围(-70~200℃)均提高。在s PS的玻璃化转变温度附近,s PS/PDM S梯度膜比均匀膜损耗因子提高了30%。进一步对梯度结构膜力学行为及介电损耗增强效应进行了详细分析。     

sPS/PBA-aPS共混体系的相容性及分散性研究

采用自制的聚丙烯酸丁酯无规立构聚苯乙烯（PBA-aPS）核壳乳胶粒子增韧改性间规立构聚苯乙烯（sPS）,通过差示扫描量热仪（DSC）、旋转流变仪、透射电子显微镜（TEM）、扫描电子显微镜（SEM）和红外/近红外成像系统等手段研究了sPS/PBA-aPS共混体系的相容性及分散性。结果表明,PBA-aPS具有润滑和增稠双重作用;PBA-aPS的引入导致共混物的玻璃化转变温度和熔点均略有下降;在实验测试温度、频率范围内,sPS/PBA-aPS共混体系没有出现相分离,表明sPS与PBA-aPS具有良好的相容性;分散相PBA-aPS在基体sPS中分散均匀,但含量大于30 %（质量分数,下同）时,部分PBA-aPS出现团聚现象。     

Structure and mechanical properties of uniaxially oriented films of syndiotactic polystyrene and poly(2,6‐dimethyl‐1,4‐phenylene oxide) blends

The structure and mechanical properties of highly oriented films of a miscible blend of syndiotactic polystyrene and poly(2,6‐dimethylphenylene‐1,4‐oxide) (sPS/PPO) were studied in the composition range of sPS/PPO = 10/0 to 5/5. The oriented films were prepared by stretching the amorphous films of the blends. Wide‐angle X‐ray diffraction and polarized FTIR spectroscopy were used to analyze the amount of mesophase and molecular orientation. Drawing of the amorphous films of sPS and sPS/PPO blend induced a highly oriented mesophase. The mesophase content increases with increasing draw ratio and becomes nearly constant above a draw ratio of 3. Under the same draw ratio, the mesophase content decreases with increasing PPO content. The orientation function in the mesophase is as high as 0.95–0.99 irrespective of the composition and draw ratio. On the other hand, the orientation of molecular chains in the amorphous phase and mesophase increases with increasing draw ratio, and it decreases with increasing PPO content. The drawn films of pure sPS show high strength and high modulus in the drawing direction, but exhibit low strength in the direction perpendicular to the drawing. In the case of sPS/PPO = 7/3 blend, however, the ultimate strength in the perpendicular direction was dramatically improved compared with that of pure sPS and the ultimate strength in the parallel direction was similar to that for the oriented pure sPS. The improved mechanical properties in the sPS/PPO blends were discussed in relation to the structural characteristics of the sPS/PPO blend system. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91:2789–2797, 2004